Thermocouple



Patented oet. 22,1949

THERMOCOUPLE Hector Rabezzana, Flint, Mich., assignor to Gen- V eralMotorsy Corporation, Detroit, Mich., a corporation of Delaware e Application october 2s, 1939, serial No. 391,192

' f s claims. (ci 13s-,4)

yMy invention rvrelates to thermocouples of the vtype designed to screw into a threaded opening in an internal vcombustion engine in which respect theybear a certain resemblance to spark plugs of conventional form, and the object of my invention is to provide an impro'ved thermocoupleof that type such.for example as is illustrated in the accompanying drawing and is hereafter described and claimed.

y In the drawing:

- lFigure 1 is a view showing aportion of an in ternal combustion engine in side elevation, and

Y f illustrating'the way in which my improved therymocouple is installed to measure the tempera- Al5 ture of exhaust gases flowing from an engine.

Figure 2 is a view showing my improved 'thermocouple in section, and upon a larger scale, the position of the plane upon which the section is talgen being indicated by the line 2 2, Figure 1. Figure 3 is a view showinga section upon a transverse plane indicated bythe line `3 3, Figure 2..

Referring now to the drawing wherein the pre- -ferred form of myinvention is illustrated, the ynumeral 5 designates the metallic shell of my Vimproved thermocouple; the same being hollow and tubular in form and having an externally threaded portion to screw into a threadedopening in the exhaust manifold 6, of an internal combustion rengine l'shown conventionally and in side elevation in Figure 1. f

rWithin the shell 5 is a memberA 8 made o porcelain or equivalent insulating material and which is held in place by a tubular member 9 86 made preferably of metal, and the inner end of which engages said insulating member; said member 9 being held in place by an inturned ange I0 at the outer end of the shell 5. The

-' insulating member has anienlarged central por- 40 tion I I las shown; and suitable yieldable gaskets I2, I3 are provided between the insulating member Aand the shell to prevent injury tovsaid member as the parts are assembled.

Theinsulating member 8 has a central longifr 5 tudinally extending passage through which a wire I IIy of lconstantan or equivalent material xf tends, while the second element of the thermocouple consists of an iron wire I5 which extends 5 along a longitudinally extending groove or passage I6 in the exterior of the shell 5 and to a v point beyond the upper end thereof.

Y end of thepassage I6 is made tapering in form, ,y j and a conical metallic wedge I1 is driven into said 55 taperedvend portion to hold the wire I5 in place t and which tubular member is held in place by an inturned flange at the outer end ofl said shell;

'I'he outer relative to the shell and within thegroove or passage along which it extends. The inner ends of the wires I4, I5 which are exposed to the exhaust gas the temperature. of`

'which is to be measured, are secured together, 5

as indicated by the numeral I8; and`the outer ends thereof lead to the terminals of a millivoltmeter or equivalent instrument for indicating electrical potential, as is usual in the use of thermocouples to indicate the temperature at the' 10 joint or junction between dissimilar metals connected together and subjected to heat.

While I have referred to the thermocouple elements or wires I4 and I5 as being of constanten, and of iron, elements of other metals or alloys l5 may be used, so long as an electrical potential will be produced when the junction between the two selected is heatedyand itf will be appreciated that while the measuring instrument contem# f plated depends lupon potential for its operation, it will commonly be calibrated so that its readings will indicate temperatures in degrees at the junction'between the thermocouple elements which are subjected to heat. t f

Having thus described and explained my invention, I claim and desire to secure by Letters Patent:

1. In a thermocouple, a 'metallic shell tubular in form and having an externally threaded portion, and a longitudinally extending groove in its 30 periphery; an insulating member within said shell and having a. longitudinally extending pas. sage; means for securing said insulating member in place within said shell; and two wires of dif-` ferentmaterials the inner ends of which are sev cured together and which wires extend one through the passage in said insulating member, and the other along Ythe groove aforesaid in the periphery of said shell. f 1

2. In a thermocouple, a metallic shell `tubular 40 in form and having an externally threaded portion; an insulating member within said shell and having a longitudinally extending passage; a tubular member within said shell and the. inner end of which engages said insulating member,l

kand two wires voi different materials the -inner ends of which are secured together and onefof which extends through the passage in said insu'- 50 lating member, and the other of which extends along said shell and beyond the outer end thereof.

3. In a thermocouple, a metallic shell tubular inform and having an externally threaded portion, and a longitudinally extending groove the-515v outer` end of `whichy is tapering in form; an insulating member within said shell and having a longitudinally extending' passage; means for se-r curing said insulating` member inplace within rsaid shell: two wires of different materials the v inner ends of which are secured together and which wires extendone through the passage in said insulating member, and the other along the groove aforesaid'and beyondthe outer end of ysaid shell; anda conical wedge Within the tapered f outer end of said groove for holding one of said Wires in place within said groove.r f f 4; In a thermocouple,a metallic shell tubular f 1n form and having an externally threaded por' tion, and a longitudinallyy extending groove the outer end of which is taperingy in form; an insulating member within said shell and having a l longitudinallyy extending passage; a tubular member kwithin said shell and the inner end oI which engages said insulating member, andwhichtubu-` lar member is held in place by an inturned ange at the outer end of said shell; two wires of differy ent materials the lnnerfends of which are ysecured together and whiohwires extend one through the ypassage in said insulating member, and the other f along the groove aforesaid and beyond the outer endof said shell; and ka conical wedge within the tapered outer end ai said groove forholdingone f of said Wires'ln place within ysaid groove.

' -5. Ina,` thermocouple, a metallic shell 'tubular in form and having an externally threaded portion', and' a ylongitudinally extending groove; an

' insulatingmember within said shell and having a longitudinally extending passage; means. for se-k n n l curing said insulatingfmember yln place within -said shell; two wires of different materials the inner ends of which are secured together and which wires extend rone through the passage in said insulating member, and the other along the groove aforesaid and beyond the` outer endr of n n said shell; and afwedge within the outer end of said groove for holding one of said wires in place within said groove.

, yHVEcVJToRRAREzzANA; 

